HU208332B - Process for producing isophthalic acid-based unsaturated polyester resin - Google Patents

Abstract

During the 1st stage of a polycondensn. reaction for the prepn. of isophthalic acid based unsatd. polyester resin, the following cpds. are also present in addn. to isophthalic acid: 35-85 (pref. 40-70) mol.% of the total glycol concn. 0.01-2 wt.% (based on total reaction mixt.) of di:methyl or di:butyl-phthalate accelerator and opt. catalyst. The 1st polycondensn. stage proceeds at 180-230 deg. C until a 50-60 mg KOH/g acid value is reached. - During the 2nd stage when maleic=anhydride or other di:carboxylic=acid components are added together with the remainder of the total quantity of glycol, the reaction proceeds in the presence of customary catalyst at 180-230 deg. C to an acid value of 2-50 mg KOH/g. The resin is cooled to 140-190 deg. C when vinyl monomer and inhibitor are adde

Description

The present invention relates to a process for preparing an isophthalic acid-based unsaturated polyester resin.

It is known that the preparation of mixed unsaturated polyesters containing an isophthalic acid component, when all dicarboxylic acid and glycolic components are added at the same time, i.e. in a single step polycondensation, requires a very long reaction time.

A two step process is generally employed to shorten the reaction time. These procedures (e.g.

No. 904,533 In the first step of the polycondensation, the isophthalic acid is reacted with the total amount of glycol components to a low acid number and in the second step, the additional dicarboxylic acid components are added and the reaction is continued until a low acid number is obtained. In this way, the reaction can be accelerated to some extent compared to the one-step reaction.

Other methods achieve the shortening of the first reaction step using a catalyst (French Patent No. 1,547,290).

The disadvantage of the known two-step processes in carrying out the polycondensation reaction is that the high excess glycol used in the first stage necessitates an extremely high capacity reflux column and the reaction temperature can be increased more slowly than desired to avoid significant loss of glycol.

The object of the process of the invention is to reduce the reaction time required for the preparation of isophthalic acid-based mixed unsaturated polyesters by eliminating the above disadvantages.

The invention is based on the discovery that when the synthesis of a mixed unsaturated polyester containing isophthalic acid is carried out in the first stage of the synthesis, only 35-85, preferably 40-70 mol% and 0.01-2 of the total glycol content is added to the isophthalic acid. by weight, dimethyl or dibutyl phthalate accelerator is added and optionally with a known catalyst, polycondensation is continued until an acid number of 5-60 mg KOH / g is added, followed by addition of other dicarboxylic acids and the remaining amount of glycol, optionally using known catalysts. continued polycondensation to an acid number of 2 to 50 (preferably 2040 mg KOH / g), the total reaction time is about 30% shorter than in conventional two-step syntheses where all glycol is added at the beginning of the reaction. This finding is surprising because it was expected that the reduction of excess glycol in the first stage would result in a decrease in reaction rate.

The present invention relates to a process for the preparation of mixed unsaturated polyester resins containing isophthalic acid by polycondensation of isophthalic acid, maleic anhydride or other dicarboxylic acids and dialcohols, so that at the start of polycondensation, 70 mol% and 0.01 to 2% by weight of dimethyl or dibutyl phthalate accelerator based on the weight of the reaction mixture, optionally in the presence of a known catalyst, are added to complete the first stage of post-condensation at 180-230 ° C with 560 mg KOH / g then add maleic anhydride or other dicarboxylic acid components and the remainder of the total glycol, followed by condensation at 180-230 ° C with 2-50 mg KOH / g in the presence of a known catalyst. and the resin is cooled to 140-190 ° C and is known in the art n vinyl monomer and inhibitor are added.

Known catalysts are preferably tin (II) chloride or tetrabutoxy titanate.

Other dicarboxylic acids are preferably fumaric acid, phthalic anhydride, adipic acid, sebacic acid, preferably ethylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol or a mixture thereof.

According to the invention, in the first stage, the substances defined above are reacted in a melt at 180-230 ° C to obtain an acid number of 5-60 mg KOH / g, then the reaction mixture is cooled to 140-170 ° C and the second is added. . Subcondensation is continued at 180-230 ° C to an acid number of 2-50, preferably 20-40 mg KOH / g.

After completion of the reaction, the melt is cooled to 140-190 ° C and used in a commonly used copolymerizable unsaturated monomer, preferably vinyl monomer, e.g. dissolved in styrene. The resin solution may contain from 0.001 to 1% by weight of a commonly used inhibitor, e.g. hydroquinone, benzoquinone, tert-butyl catechin.

An advantage of the process according to the invention is that by using it the reaction time of the resin cooking can be reduced by 25-40%.

The following examples illustrate the process of the invention.

Example 1

a) 773.8 g of dipropylene glycol and 6.8 g of dibutyl phthalate accelerator are heated to 150 ° C and 581 g of isophthalic acid are added with stirring. The reaction mixture was gradually heated to 200 ° C with constant stirring and purge of nitrogen gas. The resulting water vapor is passed through a packed column. The reaction was continued until the acid number was 40 mg KOH / g. At this time, the reaction mixture was cooled to 160 ° C and 146.3 g of 1,2-propylene glycol, 343 g of maleic anhydride and 0.17 g of hydroquinone were added. The mixture was re-heated to 200-210 ° C and stirred under nitrogen with a stream of nitrogen until 30 mg KOH / g acid. The polyester resin is then cooled to 140 ° C and dissolved in 709 g (containing 0.1 g of hydroquinone) in styrene.

b) For purposes of comparison, the amounts of the substance described in Example a) are made into the ester resin except that this time all glycols are added in the first stage of the reaction and no dibutyl phthalate is added. In the second reaction step, maleic anhydride and hydrochloric acid are added

HU 208 332 B nont. Otherwise, the procedure of Example a) is followed.

The composition of Examples a) and b) is given in Table 1, and the reaction times for the syntheses are shown in Table 2.

Table 1

Composition of polyester

Example 1 / a 1 / b /. platoon isophthalic 3.5 mol 3.5 mol dipropylene 5.775 moles 5.775 moles 1,2-propylene glycol - 1.925 moles dibutyl phthalate 0.5% by weight - Section 2 1,2-propylene glycol 1.925 moles - maleic anhydride 3.5 mol 3.5 mol

Table 2

Example 1 / a 1 / b Reaction stage 1, hour 4.5 6.5 Reaction stage 2, hour 4.0 7.5 Total reaction time, hours 8.5 13.0

Table 2 shows that the reaction time of the process of the present invention (Example 1a) is 4.5 hours, or 34%, shorter than the conventional two-step process.

Example 2

a) 319 g of 1,2-propylene glycol, 8.17 g of dibutyl phthalate accelerator and 0.82 g of tin (II) chloride catalyst are heated to 100 ° C. 498 g of isophthalic acid are added with stirring. The reaction mixture is gradually heated to 200 ° C while stirring and purging with nitrogen gas. The water vapor is passed through a packed column. The reaction was continued until an acid number of 5 mg KOH / g was reached. At this time, the reaction mixture was cooled to 170 ° C and 433 g of 1,2-propylene glycol, 0.26 g of hydroquinone and 588 g of maleic anhydride were added. The temperature was raised to 220 ° C and the reaction continued until 20 mg KOH / g acid was obtained. The polyester resin is then cooled to 170 ° C and dissolved in 1081 g of styrene containing 0.26 g of hydroquinone.

b) For comparison, with the amounts of material described in Example a), a polyester resin is prepared except that this time all glycols are added at the beginning of the reaction and no dibutyl phthalate is added. Otherwise, the procedure of Example a) is followed.

The compositions of Examples a) and b) are shown in Table 3, and the reaction times for the syntheses are given in Table 4.

Table 3

Λ polyester composition

Example 2 / 2 / b /. platoon isophthalic 3 moles 3 moles 1,2-propylene glycol 4.2 mol 9.9 mol dibutyl phthalate 1% by weight - SnCl ₂ 0.1% by weight 0.1% by weight Section 2 1,2-propylene glycol 5.7 mol - maleic anhydride 6 moles -

Table 4

Comparison of reaction times

Example 2 / 2 / b Stage 1, hour 9 12 Stage 2, hour 6 10 Total reaction time, hours 15 22

Table 4 shows that the reaction time of the process according to the invention (Example 2a) is 7 hours, i.e. 32%, shorter than that of the conventional process.

Example 3

(a) 198.4 g of ethylene glycol, 299.5 g of neopentyl glycol and

20.6 g of dibutyl phthalate accelerator are heated to 150 ° C and 531.2 g of isophthalic acid are added with stirring. The reaction mixture was heated to 200 ° C with stirring and bubbled nitrogen gas, and the water vapor was passed through a reflux column. The reaction was continued until the acid number was 10 mg KOH / g. At this time, the reaction mixture was cooled to 160 ° C and 357.1 g of ethylene glycol was added,

627.2 g of maleic anhydride and 0.28 g of hydroquinone. The temperature is raised to 200 ° C and the reaction is continued until the acid number is 30 mg KOH / g. 5.6 g of tetrabutoxy titanate catalyst are added and the polycondensation is continued to 5 mg of KOH / g acid.

The polyester is then cooled to 170 ° C and dissolved in 1188 g of styrene (previously dissolved in benzoquinone 0.28).

b) For comparison, with the amounts of material described in Example a), another polyester resin is prepared, except that this time all glycols are added at the beginning of the reaction and no dibutyl phthalate is used. Otherwise, the procedure of Example a) is followed.

The composition of Examples a) and b) is compared in Table 5 and the reaction times in Table 6.

HU 208 332 Β

Table 5

Composition of polyester

Example 3 / a 3 / b Section 1 isophthalic 3.2 mol 3.2 mol ethylene glycol 3.2 mol 8.96 mol neopentylglycol 2.88 mol 2.88 mol dibutyl phthalate 2% by weight - Section 2 ethylene glycol 5.76 mol - maleic anhydride 6.4 mol 6.4 mol tetra-titanate 0.3% by weight 0.3% by weight

Table 6

Comparison of reaction times

Example 3 / a 3 / b Stage 1, hour 7 11 Stage 2, hour 10 12.5 Total reaction time, hours 17 23.5

Table 6 shows that the reaction time of the process of the present invention (Example 3a) is 6.5 hours, or 27.6%, shorter than the other case.

Claims (4)

PATENT CLAIMS A process for the preparation of isophthalic acid-containing mixed unsaturated polyester resins by polycondensation of isophthalic acid, maleic anhydride and other dicarboxylic acids and diaic alcohols, characterized in that, in addition to the isophthalic acid component, 70 mol% and 0.01 to 2% by weight of dimethyl or dibutyl phthalate, based on the weight of the reaction mixture, optionally in the presence of a catalyst, are added to complete the first stage of polycondensation at 180-230 ° C. Add KOH / g acid, then add maleic anhydride and other dicarboxylic acid components, as well as the remainder of the total glycol content and continue polycondensation at 180-230 ° C in the presence of 2 to 50 mg KOH / g, optionally in the presence of a catalyst. until the acid number is reached, the resin is cooled to 140-190 ° C and vinyl monomer known in the art. t and an inhibitor are added. The process of claim 1, wherein the second stage of polycondensation is continued until an acid number of 20-40 mg KOH / g is reached. 3. A process according to claim 1 wherein the catalyst is tin (II) chloride or tetrabutoxytitanate. 4. The process of claim 1 wherein the vinyl monomer is styrene and the inhibitor is hydroquinone.